Gel filled electrical connector

ABSTRACT

An environmentally protected electrical socket and plug assembly retains environmental security throughout repeated connections and disconnections. The socket and plug assembly includes a socket containing an electrical conductor and adapted to insertably receive a plug, an environmental sealant at least partially filling the socket so that the sealant is at least partially displaced from the socket when the plug is inserted into the socket, and an elastomeric containment means for containing displaced sealant when the plug is inserted into the socket and for urging the sealant back into the socket when the plug is removed.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a Rule 60 Continuation of U.S. Ser. No. 08/099,013, filed Jul.29, 1993, now U.S. Pat. No. 5,406,702, which is a Rule 60 Division ofU.S. Ser. No. 07/802,950, filed Dec. 3, 1991, now U.S. Pat. No.5,246,383, which is a Continuation-in-Part of U.S. Ser. No. 07/791,749,filed Nov. 12, 1991, now U.S. Pat. No. 5,195,125, which is a Rule 60Continuation of U.S. Ser. No. 07/584,325, filed Sep. 17, 1990, now U.S.Pat. No. 5,111,497, all of which are incorporated herein by referencefor all purposes.

BACKGROUND OF THE INVENTION

The present invention relates to the field of electrical connectors,especially for telephone communication equipment, and more particularlyto environmentally protected electrical connections. Most particularly,in one embodiment the present invention provides a method and apparatusfor protecting telephone jacks from moisture and corrosion, such asoften found in coastal regions, islands, and the like.

Telephone line connections at subscriber locations are commonly madewith the RJ11 type of plug and socket connector. These connectors areexemplary of electrical connections susceptible to failure fromoxidation, corrosion, humidity, salt, and the like, especially in thepresence of a live voltage on the conductors within the connector.

For example, it is sometimes difficult to establish and maintain anadequate environmental seal in a removable male RJ11 plug, particularlywhen wires lead from the male RJ11 plug. Accordingly, moisture and otherenvironmental contaminants are allowed to enter such plugs, sometimesresulting in corrosion and/or failure of the connection of the tip andring connections in the socket/plug combination. RJ11 sockets arelikewise subject to moisture contamination and corrosion, as well asbeing subject to dust buildup. In hot, humid environments such as inFlorida and along the Gulf Coast of Texas, failure can occur withinseveral months of installation. Servicing these failures is costly forthe consumer or the telephone company.

Sometimes problems have also arisen in connection with test ports forcustomer telecommunications equipment such as remote terminals atcustomer facilities, described in the parent application, and the like.It is often desirable to provide an RJ11 connector of the type wellknown to those of skill in the art, or other such connector, at anexternal location at subscriber facilities such as a junction boxleading to a house or a remote terminal of the type described above.Previously, such access is provided by installing a female RJ11 socketat such locations which is normally connected to a male RJ11 plug. Thetip and ring wires (among other wires in some cases) lead from thefemale RJ11 socket, and connect to tip and ring connections in the maleRJ11 plug, thereafter leading into the subscriber facility. When it isdesired to connect test equipment to the RJ11 female socket, the plug isremoved, and another male RJ11 is inserted into the female socket,thereby providing tip and ring connections for the test equipment. Eventhough the equipment may be contained in a protective housing, sucharrangements are sometimes subject to much of the samemoisture/corrosion degradation.

It would therefore be desirable to provide an improved method andassociated apparatus for protecting plug and socket electricalconnectors from the environment. In particular, an environmentallyresistant RJ11 plug and socket apparatus would be especially desired.

SUMMARY OF THE INVENTION

An improved method and apparatus for environmentally protectingelectrical connections are disclosed which provide in variousembodiments for the previously recited desirable features, as well asmany others obvious to the ordinary skilled electrical connectiondesigner after reviewing this disclosure. In a preferred embodiment theinvention provides for an environmentally protected electrical socketand plug assembly that retains environmental security throughoutrepeated connections and disconnections. For example, in the case of anRJ11, the present invention provides for environmental protection afterrepeated electrical connection and disconnection of telephone equipment.

An improved socket and plug electrical connector is disclosed. Accordingto one embodiment the invention includes a socket containing anelectrical conductor and adapted to insertably receive a plug, anenvironmental sealant at least partially filling the socket so that thesealant is at least partially displaced from the socket when the plug isinserted into the socket, and an elastomeric containment means forcontaining displaced sealant when the plug is inserted into the socketand for urging the sealant back into the socket when the plug isremoved.

A further understanding of the nature and advantages of the inventionmay be had with reference to the following figures and description.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is an exploded view of an RJ11 embodiment of the presentinvention;

FIGS. 2A and 2B are cross-sectional views of an RJ11 embodiment,connected and disconnected;

FIG. 3 is a front view of an RJ11 wall plate and exposed gel surface;

FIG. 4 illustrates a gel filling fixture; and

FIG. 5 is an angled front view of an RJ11 socket.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An RJ11 wall socket and plug apparatus 1 is illustrated in the FIG. 1exploded view. The socket and plug apparatus 1 includes a female RJ11socket assembly 10, which comprises a female RJ11 socket 20, and anelastomeric containment diaphragm 30 mounted on the back of the socket20. The contacts 40 are housed within the socket 20, and the wires 45connect to the contacts 40. The wires 45 pass through containmentdiaphragm 30 individually, or, as illustrated, together through a commonpassage. The socket and plug apparatus 1 further includes an RJ11 plug50 and a faceplate 60 having an opening 65 through which the RJ11 plug50 may connect to the RJ11 socket assembly 10. In order to protect thesocket and plug apparatus 1 from moisture and other corrosives, socketassembly 10 is filled with an environmental sealant. The environmentalsealant is preferably a hydrophobic dielectric in order to excludemoisture and insulate the wires and contacts. Gels are preferred, withthe most preferred being silicone gels. The preferred gels have acohesiveness greater than their tack (adhesion to other surfaces), sothat when the plug is removed from the socket the gel will release theplug rather than some portions clinging to the plug and separating fromthe main body of gel within the socket. The gel requires a sufficientadhesion, however, so that it will form an acceptable seal around thecontacts, wires, and other portions of the apparatus in need ofenvironmental protection.

The sealant should have a hardness sufficient to provide lastingprotection against environmental contaminants. On the other hand, thesealant should be soft enough to be displaced by the plug and conform tothe shape to the socket assembly and adequately seal it. The gel'shardness also impacts a customer preference: the ability to hear a clickwhen the RJ11 plug is fully inserted and latches into the RJ11 socket.If the sealant is too stiff, this click will be muted.

The sealant's elasticity is also an important characteristic, as ithelps to return the sealant to protective placement when the plug isremoved.

A wide variety of sealants are available for this use, including, forexample, elastic hot melt materials, greases, and flexible epoxies.Preferably the sealant is a dielectric gel such as aliphatic urethanegels, urea gels, silicone gels, and thermoplastic gels likestyrene-ethylene-butylene-styrenes, including those disclosed in U.S.Patent Nos. 4,634,207; 4,600,261; 4,643,924; 4,865,905; 4,662,692;4,595,635; 4,680,233; 4,716,183; 4,718,678; 4,777,063; and 4,942,270,which are completely incorporated herein by reference for all purposes.Yet another preferred gel is Dow Sylgard gel.

Preferred gels used in conjunction with the present invention includethose having a cone penetration value from about 50 to about 350×10⁻¹mm, preferably about 100 to about 300×10⁻¹ mm, and most preferably about100 to about 250×10⁻¹ mm. Preferred gels also have an ultimateelongation of at least about 50%, preferably at least about 100%, andmost preferably at least about 200%. Alternatively from conepenetration, another measurement for hardness is Voland hardness. TheVoland hardness is generally measured on a Voland texture analyzerapparatus. Voland hardnesses from about 15 grams to at least about 50grams are acceptable for the gel, with preferred gels having Volandhardnesses from about 20 to about 40 grams.

In the embodiment of FIG. 1, the preferred environmental sealant is asilicone gel 70 having a Voland hardness of about 31±6 grams, a stressrelaxation of about 28±10%, and a tack of about 17±5 grams. Socketassembly 10 is preferably substantially completely filled with gel 70,as are any interior spaces or cavities of RJ11 plug 50. When plug 50 isinserted into opening 72 of socket assembly 10, it will displace some ofgel filling 70.

The preferred embodiment therefore has features that help retain gel 70within the assembly, where it is needed. A primary feature designed forthis purpose is the elastomeric containment diaphragm 30. Thecontainment diaphragm 30 is preferably made of a flexible material suchas rubber, most preferably Santoprene rubber made by MonteSanto Corp.Other acceptable materials include flexible plastic, rubberized cloth,and essentially any flexible material that can be formed into adiaphragm or membrane may be used. The containment diaphragm 30 isflexible enough to make room for gel displaced by the insertion of theRJ11 plug 50, but it preferably is also stiff enough create a forceurging the gel 70 back into the socket 20 when the plug 50 is removed,so that the gel 70 covers and protects the contacts 40. This force alsoplaces the gel 70 under pressure when the plug 50 is inserted, and thispressure further helps to keep out corrosive contaminants. The diaphragm30 is shown mounted opposite of the opening 72 for the plug 50, whichapplies a stronger force to urge the return of stiff gels into thesocket. Preferably the diaphragm 30 has a Shore A hardness of about 20grams to about 100 grams, more preferably about 45 grams to about 75grams, and most preferably a hardness of about 55 grams to about 65grams.

The containment diaphragm 30 also has a dimple or recess 75 inside thediaphragm, forming a cavity that provides an additional pocket ofcontainment space into which gel 70 may be displaced upon the insertionof the plug 50. The diaphragm 30 is not a strict necessity for theembodiment of the invention which includes the gel adhesive coating 100on the electrical contacts, but without the diaphragm gel 70 has atendency to flow out the back of the RJ11 socket 20 and not return toits protective position within the socket 20 when the RJ11 plug 50 isremoved. This tendency is especially pronounced after many repeatedinsertions and removals of the plug.

The diaphragm 30 also works in conjunction with the gel 70 to provide aseal around the wires 45 as they exit the socket assembly, and such anelastomeric diaphragm could be usefully added to the RJ11 test ports ofparent case Ser. No. 07/791,749. Many prior systems have had a verydifficult time sealing even one wire in such a situation, let alonefour, but the combination of the diaphragm and gel seals up to eight ormore wires. This sealing of the wires could also be achieved by thediaphragm in conjunction with some other environmental sealant, such asa grease, rather than the gel, but such sealing is inferior afterrepeated reentries.

A second feature addressing the displacement of gel 70 is an expansionslot 80 at the upper side of socket 20. The expansion slot 80 providesan additional space for displacement in a different direction than thatprovided by diaphragm 30. The expansion slot 80 may optionally contain afoam rubber or spring displacement insert 90 to urge gel 70 back intoprotective position of the contacts 40 when the plug 50 is removed. Ifused, foam insert 90 is preferably a very soft, closed foam rubber, witha density of about 2 to about 15 pounds per cubic inch, a Shore OOhardness of about 10 to about 35, and a 25% compression pressure ofabout 2 to about 9 psi. One such foam is a foam sold under thedescription V710 black by Pacific Die Cut Corp. of California. V710 foamhas a density of about 7 pounds per cubic inch, a Shore OO hardness ofabout 21, and a 25% compression pressure of about 2.5 psi.

Yet another feature of the invention to enhance the gel 70 surroundingand protecting the contacts 40, includes on a portion of contacts 40 acoating 100 having an affinity for the gel 70. The contacts 40 arepreferably gold coated, and sealants tend not to stick well to the gold.As shown in FIG. 1, the coating 100 is applied to the front portion ofthe contacts 40. The coating 100 preferably forms a strong bond with thecontacts 40, and also is preferably adhesive to the sealant 70. Forgels, a suitable material is a tacky or adhesive base component of thegel. In this way, when the plug 50 is inserted, a portion of the gel 70remains attached to the front of contacts 40; the gel is stretched outand the main portion of it is pushed in front of the plug 50, but thinstrands remain attached. When the plug 50 is then removed, the gel willcontract and be pulled back to the front of the contacts 40, protectingthem. A sufficient portion of the contacts 40 must be free of thecoating so that the contacts 40 may form electrical connections with anycorresponding contacts in the plug 50. In the preferred embodiment thecoating 100 is a silicone rubber adhesive that is applied to thecontacts 40; this may be Dow Corning RTV silicone rubber sold asSilastic T silicone rubber, and having a hardness of 20 as reported byDow Corning.

Preferably the coating is applied at a preliminary stage of constructionand allowed to harden. Then when the socket assembly is filled withsilicone gel, the gel, as it cures, will bond with the coating. Ofcourse, essentially any material that forms a good bond both with thecontacts and with the sealant may be used for the coating. The coatingalso performs the useful function of sealing the holes of contacts 40 oftheir plastic holder. For this purpose the coating does not need to bondwith the gel.

The behavior of plug and socket apparatus 1 when connected anddisconnected is illustrated in FIGS. 2A and 2B. In FIG. 2A, the gelfilled male RJ11 plug 50 has been inserted into the socket assembly 10.Some of the gel 70 has been pushed into the slot 80, and another portionof the gel 70 has pushed against the diaphragm 30, causing the diaphragm30 and especially the dimple 75 to expand. In FIG. 2B the plug 50 wasremoved from the socket assembly 10, and in that process the gel 70recedes from the slot 80, and the diaphragm 30 and the dimple 75 havecontracted, to push the gel 70 back into the opening 72, to cover andprotect the contacts 40. Also shown in this drawing are gel filledconnectors 110 that are used to connect wire leads 45 to telephone linewires 115.

The qualities of the sealant interact with the other components in anumber of ways. For instance, the desirability of the foam insert 90 mayentirely disappear if the gel 70 is sufficiently tacky. In this case thegel will stick to the plug 50 as the plug is being removed, and the gelwill be pulled down from the slot 80 into the opening 72 beforereleasing the plug 50.

The characteristics of the containment diaphragm 30 also largely dependupon the nature of the sealant 70. A stiffer, i.e., harder, gel requiresa more resilient diaphragm to push the gel back into opening 72 upon theremoval of plug 50. If a grease is used, and the diaphragm is primarilyfor working with the grease to provide a superior seal around the wiresexiting from the rear of the socket assembly, the diaphragm may berather stiff. Of course, it not necessary that diaphragm 30 have auniform hardness throughout, but merely that the net effect conforms tothese guidelines. It is also generally preferably that the material ofdiaphragm 30 is compatible with the sealant, so that, for example, anycure time or ultimate hardness of the sealant is not adversely affectedby a reaction with the diaphragm.

The tackiness of the sealant may also determine the need for otherfeatures. If the sealant is sufficiently tacky, a dust cover of somesort may optionally be provided to avoid dust accumulation on theexposed surface of the sealant (when no plug is inserted).Alternatively, a tacky gel can have a less tacky surface skin 110 in theopening 72, as shown in FIG. 3. This skin can be formed chemically,depending upon the type of gel or other sealant. Gels can also beskinned by UV treatment. This skin would prevent the exposed surface ofthe gel 70 from collecting excessive dust, but would be soft enough toyield when plug 50 is inserted.

Construction

The RJ11 plug and socket sets according to the present invention may beconstructed using a number of preexisting parts. The RJ11 sockets 20 areavailable in many shapes, and a diaphragm may be easily designed to fitmost of them. The diaphragm 30 has a lip 30a extending around itscircumference. The lip 30a further includes an extension 30b whichoverlaps the portion of the RJ11 socket 20 where contacts 40 areinserted. This area may under some circumstances benefit from an evenfurther extended lip or from glue to help prevent leakage of gel duringthe filling process and before curing.

The front portions of the contacts 40 are covered with the coating 100,if desired, which is allowed to harden. The wires 45 are passed througha small hole or conductor aperture 30c in the diaphragm 30 and thecontacts 40 are inserted into the socket 20. The diaphragm 30 is thenattached to the socket 20. Thereafter, the space between the socket andthe diaphragm is filled with sealant.

Gels used as environmental sealants need to be cured before use. Beforecuring they can be quite liquid and difficult to contain properly withinsocket assembly 10. To aid in the gel filling process, a gel fillingfixture as shown in FIG. 4 is used.

The gel filling fixture 150 contains an array of filling molds 160. Thesocket assembly 10 tightly affixes to a filling mold 160, which as shownhere contains a prong 165 which leaves an empty space in the slot 80 ofthe socket assembly 10, into which gel can move when displaced duringuse. If filling mold 160 is made of a material to which the gel willstrongly adhere, a non-stick sheath 170 or mold release material may beemployed to ease the removal of the filled socket. Once the socketassembly 10 is firmly attached, the uncured gel is injected into theassembly, preferably through a needle 180. Injecting the gel through apoint near to the dimple 75 helps prevent the formation of unwanted airbubbles at the border of the gel with the diaphragm. The gel is at thispoint very runny, and the diaphragm 30 plays a significant role inretaining the liquid gel in place until it gels. Upon curing of the gel,the socket assembly can be removed from the filling mold 160. If a skinis desired on the exposed surface of the gel, it can be formed at thistime.

To provide a tight-seal between the filling mold and the socketassembly, the socket 20 may be constructed with a lip as shown in FIG.5. The lip 180 fits around the filling mold 160 and helps create a tightseal. Alternatively, the filling mold 160 could be made with a lip tofit about the socket 20.

Examples

Plug and socket assemblies prepared in accordance with this inventionwere tested under extremely harsh conditions to evaluate theirenvironmental resistance. Fifteen connection/disconnection reentrieswere performed with each socket and plug. A first group of sockets andplugs were then subjected to immersion in salt water for fourteen daysand still exceeded isolation resistance requirements between variousterminals while immersed. A second group was exposed salt fog for thirtydays, and also exceeded isolation resistance requirements betweenvarious terminals. These test results are far superior to thoseobtainable with comparable prior art socket and plug assemblies.

Conclusion

The inventions claimed herein provide a substantially improved methodand device for environmentally protecting electrical socket connections.It is to be understood that the above description is intended to beillustrative and not restrictive. Many embodiments will be apparent tothose of skill in the art upon reviewing the above description. By wayof example the inventions herein have been illustrated primarily withregard to RJ11 telephone sockets, but teachings herein can also beapplied to other electrical socket connections, such as power outletsockets in a high humidity area such as an oil rig. By way of furtherexample, the specific embodiments described herein have employeddiaphragms surrounding the circumference of the socket and mounteddirectly opposite the entry point of the plug, but both of thesecharacteristics could be varied. By way of still further example, thespecific connectors and the roles of the male and female connectorsdisclosed herein could readily be reversed or altered. The scope of theinventions should, therefore, be determined not with reference to theabove description, but should instead be determined with reference tothe appended claims, along with the full scope of equivalents to whichsuch claims are entitled by the ordinary skilled artisan.

What is claimed is:
 1. An environmentally sealed electrical connectorreceptacle comprising:a) a socket capable of receiving an electricalplug and forming an electrical connection therewith upon insertion ofthe plug into the socket; b) an environmental sealant disposed withinthe socket; c) an elastomeric diaphragm mounted to the socket opposite aside of the socket capable of receiving the plug, said diaphragmexpanding to receive any sealant displaced by insertion of the plug andproviding sufficient force opposing displacement to seal the insertedplug; d) at least one passage within the diaphragm; and e) at least onewire passing through said at least one passage and connecting with saidsocket.
 2. The environmentally sealed electrical connection receptacleof claim 1, wherein said environmental sealant comprises silicone gel.3. The environmentally sealed electrical connection receptacle of claim2, wherein said silicone gel has a Voland hardness from about 15 gramsto about 40 grams, and wherein said elastomeric diaphragm comprisesSantoprene rubber having a Shore A hardness from about 45 grams to about75 grams.
 4. The environmentally sealed electrical connection receptacleof claim 3, wherein said socket further comprises at least oneelectrical contact having a front portion coated with a silicone rubberadhesive, said contact connected to said at least one wire.
 5. Anenvironmentally sealed electrical connector comprising:a) a socketincluding at least one electrical conductor, said socket adapted toinsertably receive a plug; b) an environmental sealant at leastpartially filling said socket, whereby said sealant is at leastpartially displaced from said socket when said plug is inserted intosaid socket; and c) an elastomeric means, coupled to said socket, forcontaining said sealant when said plug is inserted into said socket. 6.The electrical connector of claim 5, wherein said elastomericcontainment means further urges said displaced sealant to return withinsaid socket when said plug is removed.
 7. The electrical connector ofclaim 5, further including an expansion slot in communication with saidsocket.
 8. The electrical connector of claim 7, further including adisplacement insert within said expansion slot.
 9. The electricalconnector of claim 5, wherein said at least one conductor comprises acontact partially coated with a coating forming a bond with both saidcontact and said sealant.
 10. The electrical connector of claim 5,wherein said environmental sealant has a Voland hardness of about 15grams to about 50 grams.
 11. The electrical connector of claim 5,wherein said environmental sealant has a Voland hardness of about 25grams to about 35 grams.
 12. The electrical connector of claim 11,wherein said environmental sealant has a tack of about 12 grams to about22 grams.
 13. The electrical connector of claim 5, wherein saidenvironmental sealant comprises material selected from the group ofaliphatic urethanes and styrene-ethylene-butylene-styrenes.
 14. Theelectrical connector of claim 5, wherein said environmental sealantcomprises silicone gel.
 15. The electrical connector of claim 14,wherein said at least one conductor comprises a contact partially coatedwith a coating forming a bond with both said contact and saidenvironmental sealant, wherein said coating is a silicone rubberadhesive.
 16. The electrical connector of claim 5, wherein said at leastone conductor comprises a plurality of conductors including a pluralityof wires passing through a conductor aperture in said containment means,wherein said containment means and said sealant environmentally sealsaid conductor aperture.
 17. The electrical connection of claim 5,wherein said elastomeric containment means comprises an elastomericcontainment diaphragm having a Shore A hardness from about 45 grams toabout 75 grams.